Hi Brian,
Stress cracks lead to this, replace your crank with the best one you can find. I have an SC crank that needs pins, and it should be good to go, I would be willing to sell it- I believe it's a STD/STD. Please PM me if you'd like more information on it. Enjoy your evening.
These pictures are from a motor that still ran, but would not idle worth a darn, it never got to the point of total catastrophe!
James
